1. Field of the Invention
The present invention relates generally to a jet pump structure for a fuel tank installed in a vehicle such as an automobile vehicle. More specifically, the present invention relates to a jet pump structure for a fuel tank having first and second fuel chambers therein, wherein fuel stored in the first chamber is effectively transferred to the second chamber using jet swirl flows of return fuel which has been oversupplied to an engine.
2. Description of the Background Art
Recently, there has been a large demand for effective layout of a fuel tank so as to enlarge so-called utility space particularly in a passenger car. To satisfy this demand, there has been a type of the fuel tank which straddles the driving system components or the exhaust system components.
For example, Japanese Utility Model Publication (Jikkai Sho) 57-109921 discloses a fuel tank structure having a bottom wall which projects inwardly so as to avoid interference between the tank bottom wall and other functional parts.
In this type of the fuel tank, however, since a main fuel chamber and an auxiliary fuel chamber are formed at its lower section by the inward projection of the bottom wall, it is necessary to provide an arrangement which prevents the fuel remaining within one of the chambers from not being used. For example, a fuel feed pipe could be bifurcated into the main and auxiliary chambers through a switching valve such that when the fuel stored in the main chamber runs out, the switching valve is actuated to supply the fuel in the auxiliary chamber to the engine.
However, that structure requires the switching valve and other units such as a liquid level gauge and a control unit for actuating the switching valve automatically, which is very costly and complicated.